Beneficiation of coals

ABSTRACT

A process for producing a balled coal product from coal fines involves mixing a bridging liquid with coal fines and agitating the formed mixture in an aqueous medium to cause agglomeration of the coal particles. The coal particle agglomerates are then at least partially de-watered and fed to a balling device, together with a balling nuclei of coarse coal particles and binding oil to form a balled product in which each ball comprises at least one balling nucleus in association with coal particles derived from the agglomerates. The balled coal product is moved from the balling device when formed.

United States Patent Capes et al.

[54] BENEFICIATION OF COALS [72] Inventors: Charles E. Capes; Allan E.Mcllhinney, both of Ottawa; Richard D. Coleman, Or leans, ()ntario, allof Canada [21] Appl. No.2 880,741

[56] References Cited UNITED STATES PATENTS 2,769,537 11/1956 Reerink eta1. ..209/49 2,942,299 6/1960 Larson ..23/3 14 3,005,725 10/1961 Daniel]...264/l17 3,140,326 7/1964 Erck et al. ..264/1 17 PrimaryExaminer-Robert F. White Assistant Examiner-J. R, Hall Attorneyl5eBlanc& Shur ABSTRACT A process for producing a balled coal product from coalfines involves mixing a bridging liquid with coal fines and agitatingthe formed mixture in an aqueous medium to cause agglomeration of thecoal particles. The coal particle agglomerates are then at leastpartially de-watered and fed to a balling device, together with aballing nuclei of coarse coal particles and binding oil to form a balledproduct in which each ball comprises at least one balling nucleus inassociation with coal particles derived from the agglomerates. Theballed coal product is moved from the balling device when formed.

10 Claims, 1 Drawing Figure Patented May 23, 1972 IHVEHTOPS CHARLES E.CAPES ALLA/Y 5. Mc mum/yer RIC/MRO 0. comm/v ATTORNEYS BENEFICIATION FCOALS The present invention relates to the production of a balled coalproduct from coal fines and also relates to the upgrading orbeneficiation of coals.

The coal industry has become increasingly more mechanized over the pastfew years and this trend has resulted in the production of increasingquantities and proportions of coal fines, i.e. fine mesh coals havingparticle sizes in the range of 100 mesh (Tyler screen). Such fine meshcoals are difficult to clean and recover and the disposal andutilization of such fine mesh coals constitutes a pressing problem. Thisis not only because the loss of production represented by discarded finemesh coals is of economic significance but also because the enforcementof air and water pollution legislation means that the fines cannot bedisposed of as previously.

The failure to recover coal in the lOO mesh fraction may account for aloss in overall yield equivalent to a significant amount of the rawcoal. In view of rising recovery costs the potential value of such coalis constantly increasing. Not only this but the removal of fines fromthe effluent leaving a coal washing plant would permit good waterclarification and significantly reduce the pollution problems attendantupon coal recovery.

Most coal cleaning methods depend upon a density difference between thecoal and its impurity in order to effect a separation. Such gravityconcentration methods, however, are not practical for particles finerthan about 100 mesh and cleaning methods which depend upon differencesin the surface chemistry of the coal and of the impurities are used forsuch finer sizes. Currently the most important technique for thecleaning and recovery of fine mesh coals is froth flotation. In thishydrophobic coal particles attach themselves to air bubbles passedthrough a suspension of the particles in water and the hydrophilicimpurity particles remain in suspension. The froth, which contains thedesired coal particles, is subsequently dewatered, for example by vacuumfiltration. The flotation process becomes less effective where extremelyfine sizes of coal exist (for example of less than 200 mesh) or if thereis a considerable clay impurity content in the coal. Extremely finesizes of coal may be removed from suspension only if quite largequantities of oil, for example from 5 to 50 percent of the solid feed,are agitated with the suspension of coal in water. Two such bulk oilprocesses have previously been described. The first is the Trentprocess, which is described in Coal Age, 22 (23), 911 (1922), in whichpowdered coal, water and about 30 percent oil are beaten together toform an amalgam of cleaned coal, the oil passing into or being absorbedby the coal and the ash remaining in the water. By varying the degreeand duration of agitation and the quality and quantity of the oil, theamalgam can be made either to float or to sink and can be removedmechanically from the water and ash. In the Convertol process, which isdescribed in US. Pat. No. 2,769,537, oil is mixed with a slurry of coalin water under vigorous agitation and the product is discharged directlyto a high speed screen centrifuge. These bulk oil processes produce fineflocculated concentrate but an important aspect is the dewatering anddisposal of the material. Thus, for example, one disadvantage of theConvertol process is a loss of coal due to a gradual increase in thesize of the centrifuge screen perforations which is caused by wear aftercomparatively small throughputs. The frequency with which it isnecessary to change the screen and its relatively high cost areimportant factors in the economics of the Convertol process.

It is an object of the present invention to provide a process for therecovery of fine mesh coals which makes possible good overall coalutilization and recovery. The process also makes possible the productionof substantially coal free effluents and may be modified to provideupgraded or beneficiated coals of desired grades in a form which canreadily be handled.

In accordance with the present invention, there is provided a processfor producing balled coal from coal fines in which at least 75 percentof the particles pass through a 100 mesh Tyler sieve, (i.e. 150microns), comprising:

a. adding a bridging liquid capable of wetting the coal fines to anaqueous slurry of the coal fines,

b. agitating the resultant mixture to form agglomerates of said coalfines,

c. at least partially dewatering the agglomerates,

d. transferring said agglomerates to a balling device into which isintroduced a binding oil and balling nuclei coal particles of 05-10 mmaverage diameter,

e. balling the balling nuclei and agglomerates in said balling device toform an enlarged balled coal comprising balls in which at least oneballing nucleus is associated with a plurality of agglomerates, and

f. removing said enlarged balled coal from said balling device.

It is within the scope of the present invention to practice a process inwhich the material treated in the initial agglomeration step containsappreciable proportions of larger particles which could subsequently actas balling nuclei without the need to provide a separate feed or ballingnuclei to the balling device.

The coal particles in the coal fines are hydrophobic (or oleophilic) andthe bridging liquid which is added to the dispersion of the fines in anaqueous medium should be such as preferentially to wet only thehydrophobic coal particles to form a film over their external surfaces.When the mixture of bridging liquid and dispersion is vigorouslyagitated the wetted hydrophobic particles flocculate and compact intospherical agglomerates. The coal fines may also contain significantproportions, dependent upon the quality or grade of the coal fines, ofhydrophilic (or oleophobic) impurity particles such as of ash. Since itis desirable in some cases to up-grade or beneficiate the coal fines byremoving the ash or other impurity particles from the coal particles,the bridging liquid which is used in the preliminary agglomeration stepof the process of the present invention preferably should be such as notto wet the surface of the hydrophilic particles. Thus the bridgingliquid preferably should not contain any functional groups which arecapable of attaching themselves to the surfaces of the hydrophilicimpurity particles. If this is the case then hydrophilic particlesremain suspended in the water and can effectively be separated from thecoal particle agglomerates. Suitable bridging liquids for use in theprocess of the present invention are light hydrocarbon oils such asdomestic heating oils, illuminating oils and solvent oils, for examplefuel oil; kerosene and Varsol (tradename for a commercial oilmanufactured by Imperial Oil Co. Canada). If the coal fines do notcontain appreciable quantities of ash or other impurities andbeneficiation or upgrading of the coal is not essential then thebridging liquid may be a heavier oil which not only wets the surface ofthe hydrophobic particles but also, upon prolonged agitation, wets thesurfaces of hydrophilic particles with the result that both types ofparticle form agglomerates and may be separated from the aqueous phase.

The total amount of oil used in the mixing vessel and balling deviceshould be sufficient to ensure a good overall recovery of the desiredcoal particles from the coal fines and suitable amounts are from 5 to 50percent by weight based on the weight of the dry coal fines. Preferredamounts for the total amount of oil are from 5 to 30 percent by weightbased on the weight of dry coal fines.

The character of the flocculated or aggregated product from the firststage is somewhat dependent upon the porportion of bridging liquid used.With low proportions a fine, light textured flocculated material isproduced while higher proportions lead to coarser agglomerates which areessentially microspheres which may have diameters of up to 1 millimeter.The time taken for effective agglomeration is somewhat dependent uponthe level of agitation and, in general, the higher is the speed ofagitation then the shorter is the time required to completeagglomeration. During the agglomeration process the black slurry of coalchanges to a mixture of distinct black coal agglomerates which aredispersed in a light colored slurry comprising the water and thesuspended impurity particles. This inversion generally occurs in abouthalf the time required for complete agglomeration.

The mixing and agitation of the bridging liquid with the coal dispersionmay be carried out in any suitable type of apparatus; for instance, adrum equipped with a bladed propellor type of mixer. An apparatus inwhich a zone of high shear is produced in the annular space between asolid conically shaped rotor rapidly rotating inside another cone hasbeen found to bring about the desired agglomeration rapidly and also toserve as a blockage-resisting pump. In addition to the Premier Millmixer which was used, a modified turbine, disc or cone impeller may alsoprove suitable. Recently a flotation cell without air additions has beenemployed with good results.

After they are formed the agglomerates may be separated, at leastpartially, from the aqueous phase by use of a screen or by use of suchsize separators as elutriators, cyclones, or spirals. Alternatively, theagglomerates may be removed in a float-sink tank where the coalagglomerates tend to float and may be skimmed off by a paddle. Theunagglomerated impurities tend to sink and may be removed to waste inthe underflow. To improve recovery of the coal component a suitablysized screen, for example of 100 mesh, may be located horizontally overthe whole cross section of the floatsink tank just below the level ofthe skimming paddle.

In the next stage of the process of the invention the agglomerates arefed to a balling device, such as a rotating balling disc, together withballing nuclei, which comprise coarse coal particles having an averageparticle size diameter of from 0.5 to millimeters (corresponding to 32mesh to 10 millimeters, especially 1 to 5 millimeters (corresponding to16 mesh to 3 mesh), and also with a binding oil capable of forming aballed product in which substantially each ball comprises at least oneballing nucleus in association with coal particles derived from theagglomerates. The size of the final balled product may be controlled bycontrolling the relative rates of feed of coal agglomerates and ballingnuclei to the balling device. Good control of the final balled productsize to within the range of from 7 8 inch diameter to 1 inch diameter ispossible.

1f the balling nuclei are not fed to the balling device then while anincrease in the size of the coal particle agglomerate is achieved thesize of the balled product may increase apparently without limit and avery unsteady operation results. Furthermore, the balled productresulting merely from the balling of the coal particle agglomerates isof low strength and easily crumbles upon handling. The balled productproduced in accordance with the process of the invention reduces dustinglosses and makes possible the easy handling and classification of theproduct.

The balled product leaving the balling device has a moisture content ofthe order of from 5 to 15, more especially 8 to 12 percent, moisture.This product may be further dewatered in the centrifuges normally usedon only coarse coal fractions or by mill thermal drying of what isessentially surface moisture alternatively, of course it may be allowedto dry merely by standing. Control of the grade of the balled coalproduct may be achieved by judiciously beneficiating the coal fines inthe initial agglomeration step and by choosing coal nuclei withappropriate ash contents. High grade coal balls may be obtained by usinga bridging liquid which preferentially wets the hydrophobic coalparticles while leaving the hydrophilic impurity particles substantiallyunwetted and by using also low ash content coal nuclei in the ballingdevice. Coal nuclei having comparatively high ash contents may beupgraded by combining them with coal particle agglomerates of low ashcontent, again by using a bridging liquid which preferentially wets onlythe hydrophobic coal particles in the initial agglomeration step. Fromthis it can be seen that the process of the invention is capable ofproducing balled coal products having predictable ash contents andsuitable for a variety of different and uses.

Preferably the balling nuclei are coal chips having an average particlesize diameter of from 1 to 5 millimeters which size corresponds to 16mesh to 3 mesh.

The binding oil which is fed to the balling device together with thecoal particle agglomerates and balling nuclei preferably is a heavyhydrocarbon oil, such as Bunker C fuel oil and coal tar. The requirementhere is that the binding oil produces a coherent and relatively highstrength balled product in which the agglomerate particles are wellbonded to the balling nuclei to produce a product which may be handledwithout disintegrating. The binding oils often develop their fullstrength only after the balls are dried at, for example 100 C. The totalamounts of oil which may be used in the mixing vessel and balling discare in the range of from 5 to 50 percent by weight based on the weightof the dry coal fines. Preferred amounts of oil range from 5 to 30percent.

Suitable amounts of bridging oil used may be from 1 to 35 percent basedon the weight of the dry coal fines with preferred amounts being between1 to 20 percent. The bridging oil used in the mixing vessel wouldnormally amount to 20 to 70 percent of the total oil given above andbinding oil ranges used in the balling device may then be:

Operable amounts 1.5 to 40 percent Preferred amounts 1.5 to 24 percentThe amount of binding oil used of course should be sufficient for goodagglomerate strength i.e. between 30 to percent of the total oil used.

As mentioned above the size of the balled coal product is dependent uponthe relative rates of feed of the coal particle agglomerates and theballing nuclei to the balling device and the rate of feed of coalagglomerates to the balling device preferably is from 2 to 30 times therate of feed of balling nuclei on a weight basis. Also for most stableoperations the diameter of the binding nuclei should be equal to orgreater than about one-fourth of the desired balled coal productdiameter.

The invention will now be illustrated in more detail by reference to thefollowing Examples, in which parts and percentages are by weight unlessotherwise indicated,

EXAMPLE 1 The apparatus used in this Example was on a semipilot scaleand is as shown in the accompanying drawing, which is a diagrammaticrepresentation of the equipment. Experiments were performed with a 10percent weight by volume coal slurry, this being a concentration typicalof a coal wash plant effluent, and is described more fully hereinafter.The coal slurry was stored, under agitation, in a 45 gallon drum 1,provided with a stirrer 2. The coal slurry was pumped by means of pump 3to a mixing vessel 4 through pipe 5. A bridging liquid, namely Varsol,was pumped to the mixing vessel 4 from holding tank 6 by means of pump 7and the vessel 4 was equipped with a stirring device 8. The amount ofVarsol introduced into the mixing vessel 4 was 28 percent based on theweight of dry coal fed to the vessel 4. The mixing vessel 4 wasfabricated from stainless steel and was 9 inches in diameter by 8%inches in height with a capacity of 8.8 liters to an overflow spout 9.Coal slurry was normally pumped at 500 ml per minute into the vessel 4leading to an average residence time in the vessel 4 of 17 to 18minutes. The stirrer 8 was preferably a high intensity mixer in the formof a Premier mill consisting of a 1.6 inch diameter by 0.5 inch highcone rotating at 8,000 revolutions per minute within a housing to allowa 54: inch annulus through which the slurry was circulated by the actionof the mixer from the top to the bottom of the vessel 4. Agglomeratedcoal particles dispersed in a slurry of clay impurities flowed from thevessel 4 by means of overflow spout 9 to a float-sink tank 10 where thecoal particle agglomerates tended to float and were skimmed off by apaddle 11 while the unagglomerated ashforming material sank and drainedto waste through the underflow 12. To improve recovery of the coalcomponent, a mesh screen (not shown) was located horizontally over thewhole cross-section of the float-sink tank 10 just below the level ofthe skimming paddle 11. A multitude of air bubbles may also beintroduced at the bottom of the float-sink tank 10 to improve recoveryof the coal component in some cases. The agglomerated coal fraction wasconveyed together with coarser particles, or balling nuclei, by means ofa vibrating feeder conveyor 13 to a balling disc 14; the balling nucleibeing supplied to the feeder conveyor by suitable conventional supplymeans as generally indicated by arrow 17. The balling disc 14 was 16inches in diameter by 3 inches deep and was rotated at an angle ofapproximately 45. The disc 14 normally contained about 400 grams ofballed coal product providing approximately 7 minutes residence time inthe disc. A suction line 15 was provided at the foot of the rotatingdisc 14 to control the amount of water in the balling disc 14 sinceexcess water was found to reduce friction between the disc and the loadfed to the disc and resulted in a poor tumbling, cascading action in thedisc 14. Binding oil was fed to the balling disc 14 through feed pipe16. The process was run for at least 1 hour for a given set of operatingconditions in order to ensure a steady state. It was found that massbalances for the equipment generally were within the range of from 5 topercent of each other which indicated that a reasonably steady operationcould be attained. It may be noted that the suction line is not alwaysnecessary. For example, if a very dense binding oil is used in theballing disc, the balls would sink in the liquid and the desiredcascading action could be obtained without a suction line.

The properties of the coal fines fed to the drum 1 were as indicated inTable 1 below:

TABLE l Properties of Coal Studied by weight (dry basis) Ash 21.1 Fe OA1 0 SiO Total Sulphur Sulphate sulphur Pyritic sulphur Organic sulphur(by diff.)

Natural pH of 10% slurry approximately WET SCREEN ANALYSIS Weight Ash+590 0.3 4.1 +297 1.5 9.3 +149 5.6 6.7 +74 1 11.5 7.8 +44;; 6.7 10.0+31;1 l 1.3 10.3 +22 1. 11.4 8.5 22p. 51.9 29.9

This coal was supplied by the Avon Coal Company of St. John, NewBrunswick and was the minus 1 millimeter fraction from the wash plantslurry which is normally recovered by flotation and filtration. Itshould be noted that approximately 80 percent of the ash formingmaterial of this coal is contained in the minus 22 micron fraction.

Various coal fractions were used as the balling nuclei and theproperties of these various fractions are identified in Table 2 below.

" determined from the num er ofparticles per gram and the averageparticle densit It was found when using these coal fractions as ballingnuclei that the pellet or balled coal product size was effectivelystabilized. The product size was found to be effectively controlled bysuitably adjusting the ratio L/N where L and N are the rates of feed offine agglomerated coal and coarser coal nuclei, respectively.

During the continuous operation of the apparatus illustrated in thedrawing it was found that combustible product recovery was in the rangeof from 83 to 91 percent, that the ash content of the balled coalproduct was in the region of 5 to 6 percent but was in the region of 60to 70 percent for the underflow from the float-sink tank 10. Balled coalproduct having an average particle size of A inch diameter heldapproximately 12 percent surface moisture leaving the balling disc 14but when air dried overnight had a moisture content of less thanone-half percent.

EXAMPLE 2 A number of batch tests were performed in a high speed blender(capacity 1,000 milliliters) to study the effect on the process of thetype of oil and concentration and also the level of agitation andcontact time in the mixer 4. The coal slurry was agitated forapproximately 1 minute and an amount of oil was added as bridgingliquid. Agitation was continued for a further 10 minutes and the mixturewas then poured onto a mesh screen to allow the water containing the ashcomponent to drain through while retaining agglomerated coal. Theagglomerated product was washed with 500 ml of water and dried.Extraction with heptane and redrying followed if heavy oils were usedand then the product was finally analyzed.

The results summarized in Table 3 below indicate the effectiveness ofvarious oils and blends in recovering the combustible content fromslurrys of fine coal and also illustrate the selective ability of oilsto recover combustibles from the coal slurry while leaving the ashconstituents in suspension.

TABLE 3 Effect of Various Oils on Beneficiation Batch experiments: 55 g.(dry) coal It was found that heavy viscous oils were not readilydispersed in the coal slurry while the lighter oils tended to formweaker agglomerates. The oils mentioned in Table 3 above were generallyacceptable from the point of view of good recovery of the combustiblecontent of the coal slurry but it should be noted that the heavier, morecomplex oils, for example the Bunker C crude and coal tar, gave higherash contents in the product with but little rejection of ash material.Since an increase in temperature did not affect the performance of theoils appreciably, the difference was not considered to be attributableto the higher viscosity of the heavy oils. Rather it was concluded thatthe heavier oils contain functional groups which are able to wet the ashparticles in such a way as to render them hydrophobic and to allow themto report with the oil phase during agglomeration.

As summarized in Table 4 below it was found that a wide range of oilconcentrations could be used in order to produce good grades and providehigh recoveries of coal when a light oil such as Varsol is used.

TABLE 4 Effect of Oil Concentration on Beneficiation (see Table 3 forexperimental conditions).

"26 ml. Varsol, i.e. 20.3 g. used with 55 g. dry coal gives 37%.

Further experiments indicated that whereas approximately 8 minutes wererequired to complete agglomeration at 6,000 rpm agitation speed,approximately 18 minutes were required at the lower speed of 3,000 rpm.

While for low values of L/N good agreement between theoreticalcalculations and experimental results could be found by assuming thateach balled product contained only one coarse particle as a nucleus,i.e. by assuming that a thin layer of fine coal is laid down upon asingle nucleus, a devia tion of experimental results from theoreticalcalculations was observed for higher values of UN This deviation wasconsidered to be due to the fact that more than one coarse coal particlewas being incorporated into each balled coal product, thus increasingthe effective nucleus size and leading to larger final productdiameters. This explanation was confirmed by making an actual count on alarge number of balls to determine the number of nuclei embedded withinthe product. It was found as a result that if the product diameter isless than about twice the coarse particle or nucleus diameter, only onenucleus is incorporated in each balled product. With larger ratios forproduct to nucleus diameter, however, many nuclei are incorporated ineach ball, the number increasing with the ratio of the product diameterto the nucleus diameter. Apparently if the product size is considerablylarger than the nucleus size, some of the coarse particles or nuclei areabsorbed by existing balled products and do not initiate new balledproducts. Experimentally it was found that if the ratio of the productdiameter to the nucleus diameter was greater than about 4, the productsize tended to increase slowly. For the most stable operation thenucleus diameter should therefore be equal to or greater than aboutone-fourth of the desired product diameter. On this basis it was foundthat the experimental data could satisfactorily be represented by thewhere D represents the product diameter, P represents the number ofnuclei in each balled product, 11,- represents the diameter of thenucleus, L represents the rate of feeding agglomerated coal to theballing device in terms of mass per unit time, N represents the rate offeeding coarse particles to the balling device in terms of mass per unittime, p, represents the bulk density of the coal particles in theagglomerates in grams per cc, and p represents the true density of thecoarse coal particles used as nuclei in grams per cc.

We claim:

1. A process for producing balled coal from coal fines in which at least75 percent of the particles pass through a 100 mesh Tyler sieve,comprising:

a. adding a bridging liquid capable of wetting the coal fines to anaqueous slurry of the coal fines,

b. agitating the resultant mixture to form agglomerates of said coalfines,

c. at least partially dewatering the agglomerates,

d. transferring said agglomerates to a balling device into which isintroduced a binding oil and balling nuclei coal particles of 05-10 mmaverage diameter,

e. balling the balling nuclei and agglomerates in said balling device toform an enlarged balled coal comprising balls in which at least oneballing nucleus is associated with a plurality of agglomerates, and

f. removing said enlarged balled coal from said balling device.

2. A process as claimed in claim 1 wherein the coal fines predominantlycomprise particles not smaller than 200 mesh size.

3. A process as claimed in claim 1, wherein the coal fines comprisehydrophobic coal particles and hydrophilic ash particles and thebridging liquid is a hydrocarbon oil which preferentially wets the coalparticles while leaving the ash particles substantially unwetted.

4. A process as claimed in claim 3 wherein the bridging liquid isselected from the group consisting of fuel oil and kerosene.

5. A process as claimed in claim 3 wherein the amount of bridging liquidis from 20 to 70 percent by weight of the total of binding oil andbridging liquid used.

6. A process as claimed in claim 1 wherein the balling nuclei are coalchips having an average diameter of from 1 to 5 millimeters.

7. A process as claimed in claim 23 wherein the binding oil is Bunker Cfuel oil.

8. A process as claimed in claim 1 wherein the amount of binding oil isfrom 30 to percent by weight of one-half total of binding oil andbridging liquid used.

9. A process as claimed in claim 1, wherein the balling device isprovided with suction means for removing excess water from the ballingdevice.

10. A process as claimed in claim 1, wherein the balled coal productleaving the balling device is dried to a moisture content of at mosthalf percent by weight.

2. A process as claimed in claim 1 wherein the coal fines predominantlycomprise particles not smaller than 200 mesh size.
 3. A process asclaimed in claim 1, wherein the coal fines comprise hydrophobic coalparticles and hydrophilic ash particles and the bridging liquid is ahydrocarbon oil which preferentially wets the coal particles whileleaving the ash particles substantially unwetted.
 4. A process asclaimed in claim 3 wherein the bridging liquid is selected from thegroup consisting of fuel oil and kerosene.
 5. A process as claimed inclaim 3 wherein the amount of bridging liquid is from 20 to 70 percentby weight of the total of binding oil and bridging liquid used.
 6. Aprocess as claimed in claim 1 wherein the balling nuclei are coal chipshaving an average diameter of fRom 1 to 5 millimeters.
 7. A process asclaimed in claim 23 wherein the binding oil is Bunker C fuel oil.
 8. Aprocess as claimed in claim 1 wherein the amount of binding oil is from30 to 80 percent by weight of one-half total of binding oil and bridgingliquid used.
 9. A process as claimed in claim 1, wherein the ballingdevice is provided with suction means for removing excess water from theballing device.
 10. A process as claimed in claim 1, wherein the balledcoal product leaving the balling device is dried to a moisture contentof at most half percent by weight.